1. Field of the Invention
This invention relates to preventing access to confidential data in secure systems including, but not limited to, pay-television.
2. Description of the Related Art
In secure systems, it is usually necessary that access to data of a confidential nature should be restricted. Access to data is often restricted by encrypting the data by means of a particular encryption algorithm using a secret key. Data may then be accessed by decrypting the data using a specified key that is possessed only by authorized users. In many systems, large volumes of data may need to be frequently encrypted and decrypted at a high bandwidth. In such systems, the processing requirements for performing encryption and decryption of data at the required rate may be considerable, especially if the algorithms used are complex, requiring many calculations.
We have appreciated the need for a fast and efficient means for modifying data so that unauthorized access to the data is prevented.